1. Field of the Invention
This invention relates to a device for controlling a stop-position of an electric windshield wiper, which is used for wiping a window glass of an automobile or the like, to stop the wiper at a predetermined position (or a so-called auto park device).
2. Description of the Prior Art
Heretofore, there has been used a stop-position controlling device for an electric windshield wiper as shown in FIG. 1.
In FIG. 1, numeral 1 is a contact base rotating together with a worm wheel constituting a reduction mechanism of a wiper motor, which is composed of a first contact plate 2 of a disc form having a fan-shaped notch portion, and a second contact plate 3 disposed at a position corresponding to the notch portion apart from the first contact plate 2 and protruded from the first contact plate 2 toward the outside thereof.
To the contact base 1 are arranged a first contactor 6 communicating a power source 4 with an armature 5 and being capable of contacting with only the second contact plate 3, and a second contactor 8 connected to an off-terminal 7 and being capable of contacting with the first and second contact plate 2 and 3 at a side of a motor casing (not shown) in such a manner that the first and second contactors 6 and 8 are connected to each other through the second contact plate 3 every one rotation of the contact base 1. Further, since a wiper blade (not shown) reciprocates every one rotation of the worm wheel provided with the contact base 1, it takes a wipe-finishing position when the contactors 6 and 8 become at the connected state through the second contact plate 3.
Moreover, numeral 9 is an earth terminal of a control switch, numeral 10 a high-speed operating terminal, numeral 11 a low-speed operating terminal, and numeral 12 a movable contact connected to a wiper switch.
In the stop-position controlling device of the above mentioned structure, when the wiper switch is randomly turned off during the operation of the wiper, the movable contact 12 renders the off-terminal 7 and the low-speed operating terminal 11 into the contact state. In this case, electric current still flows through the contacting of the second contactor 8 with the first rotating contact plate 2 to continue the operation of the wiper. Then, when the second contactor 8 is separated from the first contact plate 2, the electric current is shut off from the power source 4. Thereafter, the first contactor 6 and the second contactor 8 are rendered into the contact state through the second contact plate 3, whereby the short-circuit of the armature 5 is formed to brake the operation of the wiper. Thus, the wiper can be always stopped at a wipe-finishing position.
In the conventional stop-position controlling device, however, a wiper blade 14 contacting with a surface of a window glass 13 at a given pushing force always stops at the wipe-finishing position under deformed state in one direction. As a result, the wiper blade 14 is subjected to permanent deformation under an influence of heat generated from sunlight, ultraviolet ray or the like in no use of the wiper and consequently there are caused troubles such as poor wiping, occurrence of vibration sound in the wiping and the like.
Therefore, it has been attempted to separate the wiper blade from the surface of the window glass in no use to thereby prevent the permanent deformation of the wiper blade or to arrange a wiper receiving means beneath the window so as not to come the wiper into vieww in no use. However, when the wiper blade is separated from the surface of the window glass in the wiper assembly having no wiper receiving means, the wiper blade is lifted outward every one reciprocating operation of the wiper, so that the wiping at the wipe-beginning and-finishing positions is not performed sufficiently. Further, there are some drawbacks that the structure becomes complicated, and the working sound in the lifting of the wiper is apt to be generated and the like.